I can confirm the "no issues" part (so far) as owner of a DT11 Black Edition. Haven't shot heaps with it yet, as I just put my 692 Black edition aside. I have probably shot a couple thousand now without incident, and I am not the first owner. I shoot about 200-ish cartridges a week on average, so it 's not a safe queen. Despite having just set it up with an Ergosign stock, I used it in a match last Sunday and made it to the finals. This gun just works for me.
The bead is threaded and meant for easy replacement: There are spares in different sizes in the box it came with. As with the 692 I use a bit of sticky paste to keep them secure, because the fit can become less secure if the barrel heats up the carbon. Not a flaw as such but physics, really.
As I did with the 692, I will likely order a spare carbon rib (or compare whether it's identical to the spare 692 rib). Carbon is strong, but it can chip or break if something daft happens. Never needed it for the 692, but better safe than sorry. If I come across an extra trigger unit I may buy that, just for the peace of mind. Most spares (pins, firing pin springs, leaf springs for the trigger) were already included with purchase as well as all the weights for barrels and stock.
Haven't seen anything mechanical go amiss with one yet, and I know a few people who shoot DT's.